Need help on float_io format

Need help on float_io format

[nico nieh]

In FORTRAN, the free format output of 23.35 is 0.2335000+02.
I just discovered that there is no way to let Ada print out 23.35
as 0.2335000+02. I tried AFT and EXP control parameters and I always got
2.335000+01. Do I miss something? Can any one out there tell me
what's wrong? Thanks in advance.
     Ko-Haw Nieh
     General Electric Company 
     Corporate Research and Development
     nieh@ge-crd.arpa
     518-387-7431

Re: Need help on float_io format

[stt]

This is a feature, not a bug.  Ada believes in "scientific
notation" (not "Fortran notation").  As it says in LRM 14.3.8:14,

  If EXP has a value greater than zero, then the integer part
  to be output has a *single* digit, which is nonzero except
  for the value 0.0 of ITEM.

If you feel adventurous, you can PUT the number into a string,
and then fiddle around with the string (probably easiest if
you multiply by 10 first, so all you have to do
is prepend "0." and eliminate the existing decimal point).

If you feel very adventurous, you can write your own Float-to-string
conversion routine, and then output it using PUT of a string.

Tucker Taft
c/o Intermetrics
Cambridge, MA  02138

Re: Need help on float_io format

[Alfred.Peterson]

>In FORTRAN, the free format output of 23.35 is 0.2335000+02.
>I just discovered that there is no way to let Ada print out 23.35
>as 0.2335000+02. I tried AFT and EXP control parameters and I always got
>2.335000+01. Do I miss something? Can any one out there tell me
>what's wrong? Thanks in advance.
>     Ko-Haw Nieh
>     General Electric Company 
>     Corporate Research and Development
>     nieh@ge-crd.arpa
>     518-387-7431


Yes, unfortunately, Text_Io is REQUIRED to behave as you specify above.
ARM 14.3.8 (Input-Output for Real Types) para. 13 states "If EXP has the
value zero, then the integer part to be output has as many digits as are
needed to represent the integer part of the value of ITEM [in the overloaded
procedures PUT above], overriding FORE if necessary, or consists of the digit
zero if the value of ITEM has no integer part."

The next paragrah states "If EXP has a value greater than zero, then the
integer part to be output has a single digit, which is nonzero except for
the value 0.0 of ITEM."

The ramification of the two paragraphs is that the predefined Text_Io package
can NEVER produce the output that you would like and be validable.  I believe
that the premise for the required Text_Io format is that it follows that of
the 'standard' scientific notation form for writing real numbers.

Spencer Peterson
Member of the Technical Staff
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA  15213
412-269-7608
asp@sei.cmu.edu